The present invention relates to a new and improved construction of a filter box for textile machines, especially spinning machines, which is of the type comprising a filter subdividing a box into a raw air chamber and a clean air chamber, a respective inlet opening and outlet opening is provided for the raw air chamber, and a ventilator connected at its suction side with the clean air chamber.
With such type filter boxes the inlet opening is connected with a suction conduit servicing the working positions of the machine, whereas the outlet opening, as a general rule, is in communication with a central fibre depositing system which, through the agency of suitable lines or conduits where there prevails a negative pressure, coacts with a multiplicity of filter boxes. The fibres collected in the filter box at the raw air side are removed by means of the outlet opening due to the negative pressure in the central fibre depository, by periodically opening the shutoff element.
With the state-of-the-art filter boxes the filter, separating the raw air chamber and the clean air chamber from one another, extends practically transversely with respect to the direction of the flow produced by the ventilator. Consequently, most of the fibres reaching the raw air chamber deposit on the filter. With increasing time of operation and increasing contamination of the filter surface with fibres, the pressure drop at the filter increases and the suction capacity at the working locations of the machine accordingly decreases. It is therefore necessary to rather frequently clean or empty the filter boxes. Hence, the air conveying device which generates the negative pressure in the conduits of the fibre depositing system must be designed to be relatively efficient. Thus, the heretofore known filter boxes not only require considerable investment costs but, due to the energy requirement, also high operational costs.
In certain instances the pressure fluctuations in the suction conduit or line also can be disadvantageous for the operation of the machine or even the quality of the product. On the other hand, the utilization of such filter boxes may be impossible for certain applications, if, for instance, as in the case of open-end spinning there is required an absolutely constant pressure.